Neutral salts of sulfonated products of fatty acid alkyl esters are frequently also referred to as α-sulfo fatty acid alkyl ester salts (or α-sulfo fatty acid ester salts), and are surfactants which not only exhibit favorable hard water resistance and biodegradability, but also offer excellent detergency while being mild on the skin. Further, because α-sulfo fatty acid alkyl ester salts are a reusable natural raw material, they are also useful from the viewpoint of protecting the global environment. Moreover, α-sulfo fatty acid alkyl ester salts are available commercially in the form of flakes and powders and the like, and each of these types of commercial product are readily available.
For the reasons outlined above, α-sulfo fatty acid alkyl ester salts are often blended into detergents for textile products such as clothing.
However, α-sulfo fatty acid alkyl ester salts have a distinctive raw material odor, and when added to detergents, tend to cause an unpleasant odor that can adversely effect the fragrance of the product. For example, in the case of a granular detergent product in which a granular detergent is stored inside a sealed container, when the container is opened to use the granular detergent product, the odor that has accumulated in the head space inside the container can sometimes cause the user some unpleasantness.
Further, in order to differentiate a detergent composition and enhance its commercial value, a fragrance is often added to the detergent in order to impart a favorable aroma. However, if the detergent contains an α-sulfo fatty acid alkyl ester salt, then the odor of the α-sulfo fatty acid alkyl ester salt may inhibit the development of the aroma from the fragrance, which can impair the commercial value.
It is known that the substances responsible for the odors derived from α-sulfo fatty acid alkyl ester salts (namely, the odorous components) are lactones (lactone-containing compounds). It is thought that these odorous components are generated during the production process or the like as a result of decomposition of the α-sulfo fatty acid alkyl ester salt itself or impurities derived from the natural raw materials (paragraph [0032] of Patent Document 1).